1. Field of the Invention
The present invention relates to an apparatus for detecting the number of beats per unit time in a tune.
2. Description of the Related Background Art
Music generally played in discotheques is so-called dance music which is suitable for dancing. However, it is not preferable to change the tempo every time a different piece of music is played, because people dancing in a discotheque may feel difficult to dance to the accompaniment of such tempo-changing music. On the other hand, continuously replaying the same music for a long time, because of not changing the tempo, would cause dancing people to lose their interest in the dancing. Thus, a disk jockey (DJ) to edit pieces of dance music in a discotheque handles a plurality of (for example, two) disk players in order to play the next piece of music (second tune) immediately after the completion of a currently played piece of music (first tune) through a mixer for editing. While playing the first tune with one disk player, the DJ searches for the head of the next tune in the other disk player and controls the disk rotating speed of the other player to match with both the play speeds such that play of the second tune can be started at the time the play of the first tune has been completed.
However, even if the play speeds of the first and second tunes are merely matched with each other, the connection portion between both the tunes will be found as far as rhythms thereof are not the same. Therefore, the DJ detects each number of beats per unit time, for example Beats Per Minute (BPM) of the first and second tunes, and accurately adjusts the rotation speed of the disk in the disk player so as to match both the numbers of beats.
In a conventional method for detecting the BPM, while a DJ listens to a tune, he pushes an input switch of a BPM measuring machine in response to the beat of the tune. The BPM measuring machine has an internal timer which starts measurement of time at the same time as the first pushing of the switch after the detection of the BPM is instructed by another switch and which measures a predetermined period of time, for example 10 seconds. The machine counts the number of pushing of the input switch for the predetermined period, and then calculates the counted number in the term of 60 seconds as a BPM which is displayed on a display or the like.
However, such a conventional method for detecting the BPM is a complicated work for the DJ, because he must repeatedly push the input switch of the BPM measuring machine in accordance with rhythm of the tune, and furthermore the DJ editing the connection of tunes must adjust the play speed of the next tune and set the connection timing of the tunes.